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Caption

Met-enkephalin molecule. Computer model showing the structure of the neurotransmitter met-enkephalin (methionine-enkephalin). Atoms are colour-coded spheres (carbon: dark grey, hydrogen: light grey, oxygen: red, sulphur: yelow, and nitrogen: dark blue). Met-enkephalin is one of two forms of enkephalin. Enkephalins are endorphins and are found in the central nervous system where they bind to the body's opioid receptors. Endorphins are produced in the brain by the pituitary gland and hypothalamus and act as natural pain relievers.